It is well known that two permanent magnets will attract or repulse one another at close distances depending on how the poles of the magnets are aligned. When aligned with the gravitational force vector, magnetic repulsion can be used to counteract gravity and lift an object. For the purposes of lifting an object and then moving it from one location to another location, magnetic repulsion is either unstable or too stable. In particular, opposing magnets can either be aligned such that the object remains in place but then can't be easily be moved to another location or the magnets can be aligned such that the object is easily moveable but won't remain in place but not both.
Another magnetic repulsion effect is associated with generating a moving magnetic field near a conductive object. When a permanent magnet is moved near a conductive object, such as a metal object, eddy currents are established in the conductive object, which generate an opposing magnetic field. For example, when a permanent magnet is dropped through a copper pipe, an opposing magnetic field is generated which significantly slows the magnet as compared to a non-magnetic object dropped through the pipe. This effect is described by Lenz's law.
The eddy current effect has been proposed as a means of generating magnetic lift. For example, the eddy current effect has proposed for use in “Maglev” trains (Maglev is short for magnetic levitation). In a Maglev train application using the eddy current effect, magnetic arrays of permanent magnets coupled to the train cars are moved over a conductive track. The movement of the magnetic field generated by the magnetic arrays induces an opposing magnetic field in the conductive track, which lifts the train cars. As compared to using two groups of magnets with opposing magnet fields (e.g., magnet arrays in the tracks and on the train cars), an advantage of this approach is that only one portion of the system, i.e., the train cars, require permanent magnets or some other mechanism for actively generating the magnetic field.
In operation, the magnetically equipped train is accelerated from a resting position and through a threshold velocity using some propulsive mechanism. During this period, the opposing magnet field induced in the conductive tracks is not sufficient to lift the train cars. However, once the train cars reach the threshold velocity, a sufficient opposing magnetic field is induced in the conductive tracks via the eddy current effect such that the train cars are magnetically levitated at some height over the conductive tracks.
Since the train cars must be moving to generate the magnetic lift in this manner, the system is not suitable for magnetically lifting an object while it remains in a stationary position. In view of the above, new methods and apparatus for generating magnetic lift are needed. In particular, magnetic levitation systems are needed which allow an object to be magnetically lifted while in a stationary position and while being moved from the stationary position to another stationary position.